The present invention relates to a practice golf ball, and more particularly to a practice golf ball that has high sphericity and a center of gravity consistent with a geometrical center of the ball.
In consideration of the safety of practicing golf indoors, a practice golf ball is usually employed for such purpose. The currently available practice golf balls can be generally divided into two types according to their material, namely, plastic and fibrous material practice golf balls.
FIG. 1 illustrates a conventional practice golf ball made of plastic material. A part of the golf ball is shown in sectional view in order to better show the structure thereof. The illustrated conventional practical golf ball is formed by plastic material through injection molding and is a hollow ball having a spherical shell. A plurality of through holes are provided on the spherical shell. An advantage of such plastic practice golf ball is its low manufacture cost. However, the plastic practice ball tends to deform when being struck with a club and will therefore have a center of gravity deviated from a geometrical center of the ball. This condition would cause the plastic practice ball to fly in the air along a path that deviates from a path along which a real golf ball would usually fly. In other words, practicing golf with the plastic practice golf ball does not ensure a good performance and an observed path of the flying plastic practice golf ball does not ensure a real correct path has been controlled by the golf player.
To improve the plastic practice golf ball, another type of practice golf ball made of fibrous material has been developed. U.S. Pat. No. 5,630,763 entitled "Golf Training Ball" granted to Chu Li-Tsan, also the inventor of the present invention, discloses a golf training ball made of soft fibrous material that is compressed into two semispherical halves that are then separately wrapped with a woven material. The woven material usually includes two pieces of circular fabric having the same extended area. When using the circular fabric to wrap each semispherical half of compressed fibrous material, a circumferential outer periphery of the circular fabric is gathered to locate at a center of a flat surface of the semispherical half and sewed up. The two semispherical halves wrapped with the woven fabric are then connected to one another at their flat surfaces to form a complete ball and the seam between them is sewed up with a string. Such golf training ball made of compressed fibrous material has somewhat stable center of gravity compared to the plastic practice golf ball. A disadvantage of the golf training ball disclosed in U.S. Pat. No. 5,630,763 is that the woven fabric wrapping the compressed fibrous material does not provide a smoothly curved edge along the outer periphery of the flat surface of the semispherical half. Moreover, the two semispherical halves of the compressed fibrous material are not always identical in dimensions and the circumferential outer periphery of the round fabric is not always gathered to just locate at the center of the flat surface of the semispherical half. That is, the golf training ball formed from the sewed-up two halves does not always have high sphericity and/or evenly distributed fibrous material. More specifically, the center of gravity of such fibrous golf training ball frequently deviates from the geometrical center of the ball to possibly cause a deviated fly path as would find in the case of a plastic practice golf ball.
It is therefore desired by the inventor to develop an improved practice golf ball to eliminate the drawbacks existing in the conventional practice golf balls made of plastic material or fibrous material.